N. López Perrusquia

Effect of Hydrogen on the Mechanical Behavior of API X70 Ageing

The present work reports on the effect of hydrogen on the mechanical behavior of API 5L X70 ageing. Bending test specimens underwent solution treatment in an electric induction furnace at 1100°C for 30 min under argon atmosphere and water quenching and then ageing process for five temperatures in the range between 204 to 650°C for 30 min of time exposition and water quenching, respectively. The microstructural characterization was examined by scanning electron microscopy (SEM) and matrix samples ageing showed microstructures, acicular ferritic, polygonal ferrite, bainitic-ferrite, degenerate perlite and retained austenite and energy dispersive spectroscopy (EDS) evidencing the presence of carbonitrures type Nb, Ti, V (N, C). Hydrogen was introduced in a sample of bending test, through cathodic charging, applying a current density of 50 mA/cm2. Three point bend test was carry out on specimen on API X70 with and without hydrogen and the result showed a reduction of ductility and 65% of index of embrittlement (IH). Also, samples undergoing ageing with hydrogen showed an increase in bending stress compared to a sample undergoing ageing without hydrogen, and the parameter (IH) decreased in the range of 21 to 29% due to the formation of traps. The fracture surface of bend tested samples were examined using a SEM.

Topological and Contact Force Analysis of a Knee Tumor Prosthesis

In the present work, a topological analysis of a knee tumor prosthesis using grade 5 biomedical titanium alloy material (Ti6Al4V) and an ultra-high molecular weight polyethylene insert (UHMWPE) was performed. A three-dimensional finite element analysis (FEM) model was used, taking into account the von Mises stress and the contact forces (CPRESS), using the finite element software ABAQUS that analyzes the mechanical contact between two surfaces. The contact pressure due to the contact force and shear stress from friction, especially in the contact areas in the UHMWPE and Ti6Al4V parts, to be considered occur during the following activities: (1) At the critical point of the walking cycle at 15° of femur flexion with respect to the tibia with a load of 3.3 times the body weight (BW), (2) Climbing stairs with a bend angle of 83° and 3.5 BW and (3) Squatting with an angle of 130° and 5.6 pcs (Alsamhan in J King Saud Univ Eng Sci 25:49–54, 2012, [1]; Brassard in Complicaciones de la artoplasia total de rodilla. Insall, Mexico, 2007, [2]; Buehler in J Arthroplasty 15:698–701, 2000, [3]). The Analysis of the knee tumor was performed by scanning the parts, digitizing them in STL format and debugging the images using CAD software. We performed the simulation of these three conditions using finite element analysis software, obtaining a maximum stress of 229,497 MPa in the squat condition and a displacement of 20.14 μm in this same condition. We used the von Mises failure criterion equation (Jhonson in Mecanica de contacto. Cambridge University, Mexico, 1985, [4]). For the analysis of contact forces in the joints we used the results of CPRESS and were validated with an analytical contact Hertz study (Ludema in Friction Wear Lubrication. CRC Press, Michigan, 1996, [5]). The topology indicates that there are material savings of 80%, mainly on the titanium alloy of the knee. As reference, a male Mexican patient with a weight of 70 kg and 1.70 m of height was taken.

Effect of Hydrogen on a Microalloyed Steel Permeate

In this work, we examined the influence of hydrogen into microstructure in a steel API-X60, with different heat treatments. First, all plate samples undergo heat treatment at a temperature of 1000 ∘C for 30 min. The formation of microstructures are obtained at temperatures of 204, 315, 426, 538, and 650 ∘C for 30 min and cooled in water. The permeation tests were carried out according to the modified Devanathan-Starchurski setup. Microstructural observation involved use of an optical microscope (OM) with and without hydrogen. The phases predominantly after heat treatment are bainite-ferrite, ferrite-martensite, Widmanstatten ferrite, and globular bainite. The result obtained at the condition of 204 ∘C and 315 ∘C decrease the hydrogen diffusion due to the formation of different phases. In addition, the finite element method (FEM) was used to evaluate the hydrogen diffusion on the specimens.

Characterization and Study Hard Layer on Steels Grade Machinery

The paper also presents the growth kinetics of the hard layers on the surface grade machinery steels type AISI 9840 with a boron dehydrated paste. The thermochemical treatment was performed at three different temperatures: 1173, 1223, and 1273 K, with 2, 4, 6, and 8 h treatment time for each temperature. The presence of the hard layers FeB and Fe2B formed on the surface AISI 9840 was confirmed by cross sectional observation by scanning electron microscopy (SEM), XRD analysis and the distribution of alloy elements from hard layers was confirmed by energy dispersive spectroscopy (EDS). Using the law of parabolic growth the mobility of boron was included potential influence of boron, treatment time, temperature and time incubation in hard layers. Finally, nanoindentation technique test the modulus and hardness are obtained of the FeB and Fe2B hard layers.

Growth Kinetics and Mechanical Characterization of a Hard Boron Coating on a Tool Steel

The mechanical characteristics are determined to a FeB/Fe2B coating applied in AISI L6 steel tool and blades make to cut paper. The thermochemical treatment was applied at temperatures of 1173, 1223 and 1273 K with permanence time of 0.5, 2 and 3 h for each temperature. The diffusion coefficient and activation energy for each phase is obtained for this boron coating on an AISI L6 steel. HRC test were made to establish the type of adherence (qualitative) and comparing with the VDI 3198 standard and the results were obtaining optimal classification of HF1-HF2 in condition for 3h of the three temperatures. The result by nanoidentation show hardness of 1000 - 2000 HV as well as the Youngs modulus for each present phase of the coating. Through micrographs (SEM) are showing thicknesses up to 79.52 ± 18.82 μm for FeB and 97.80 ± 20.01μm for Fe2B, a morphology sawn ́s type is evidence. Through EDS and x-ray diffraction are used to show the chemical elements formed.

Analysis of Bone Plate with Different Material in Terms of Stress Distribution

One of the most used in the field of medicine for the treatment of tibial shaft fractures internal fixation methods is by osteosynthesis plates, the most common plate limited contact dynamic compression (DCP-LC) [1]. This paper presents the results of the fracture site grade 1, where the contact plate and the bone callus area on plates made of bone (LVM stainless steel, titanium alloy different biomedical materials and cobalt alloy), in recovery conditions 1% (one week of recovery), 50% (three weeks of recovery), 75% (six weeks of recovery) and 100%. The fractured tibia bone was modeled with an ideal geometry in CAD [2], modeling of commercial DCP-LC plate was obtained by parameterization of the part using a coordinate machine equipment for the exact geometry. The finite element method for the analysis of each case under the same loads and boundary conditions is used, the results were used to determine stress concentrations in the displacement plate and the fracture callus in the load direction, to have a starting point in the optimization of the geometry from a commercial plate minimizing mass while determining that the material has faster and better biocompatibility with the human body recovery. The results obtained show that the plate under the conditions of three different types of biomaterials has a greater stress concentration in the part located in the fracture zone from stage with 1% recovery between the surfaces of the bone callus upper and lower, keeping this a significant effect on the recovery of the fracture. The compression and tension strength that occur in the intact part of the bone and the tibial fracture interface at different stages of osseous healing have been investigated, The results were compared and presented, showing that the stress distribution in the callus to 1% recovery in the stainless steel plate indicate considerable compression in the area of the callus with this causing deterioration in the area fracture because the callus is not strengthened by contact between fractured bone by increasing the recovery time, the results also indicate that the titanium plate is the one with the lower shielding effect [3] according to the distribution of contact stresses according to the recovery period in the part of callus, making it the material of which the best adaptability to the bone is obtained.

Effect of Hydrogen on the Mechanical Behavior on AISI 4140 with Borided Coatings

In this work, the mechanical behavior on AISI 4140 with boride coating and hardened quenching-tempering was studies subsequently to boriding. The boriding is conducted at temperatures 1203 and 1233 K for 7 h, after that all samples at a temperature of 1143 K for 1 h and tempering 473 K were exposed for 1 h 30 minutes. The microstructural characterization was examined by scanning electron microscopy with saw-tooth morphology of boride coatings type Fe2B. Three-point bend test was used to study the effect of hydrogen cathodic charging on the mechanical behavior of AISI 4140 with boride coatings, the results show a reduction of ductility and 58.17% of indices of embrittlement () and show a crack on the substrate due to interaction of hydrogen atom. Also, sample boride at 1203 K with hydrogen show a low decrease of the bending stress with respectively a sample boride without hydrogen and a decrease of the parameter () with 35.32% due to the formation of boride coatings.

Characterization and Fracture Toughness on AISI 8620 with Hard Coatings

The present studies characterize and evaluate the fracture toughness at the surface AISI 8620 with hard coating. The hard coatings FeB and Fe2B were formed using the boriding dehydrated paste at temperatures 1223 and 1273 K with 6 and 8 h exposure time, respectively. The presence of hard coatings formed on the surface AISI 8620 were confirmed by the classical metallographic technique combined with X-ray diffraction analysis. The distribution of alloying elements was determined by Energy Dispersive Spectroscopy (EDS). The fracture toughness of the hard coatings on AISI 8620 was estimated using a Vicker microindentation induced fracture testing of 15 and 35 μm from the surface, applying four load (0.49, 0.98,1.96 and N). The microcrack generated at the corner of the microindentation was considered as an experimental parameter and the tree model Palmqvist crack model was employed to determine the fracture toughness. The adherence of the hard coatings/substrate was evaluate in qualitative form though the VDI 3198 by testing Rockwell C and observed by Scanning Electron Microscopy (SEM). The formation of hard layers was obtained in the range of 100-130 μm, results of XRD present phases FeB, Fe2B, CrB and MnB, the values obtained of Kc are in the range of 2.3 to 4.1 MPam1⁄2 and results of acceptable adhesion HF4 patterns for conditions 6 h of treatment

Effect of Hard Coatings on Surface Gray Iron on Fracture Toughness

The characterization and fracture toughness with hard coatings formed at the surface of gray cast irons class 30 is evaluated in the present study. The formation of hard coatings was obtained out means of the pack boriding process; the treatment was carried out at temperatures of 1173 and 1223 K during 6 hours. The layers were evaluated by the techniques of X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and microindentation across the thickness of the iron boride layer. Three-point bending tests are carried out to examine the fracture toughness of gray cast irons boriding according to the ASTM 399 standard. Consequently, the stress intensity factor was evaluated by means of the finite element method (FEM) using the package ANSYS 11. 0 creating a two-dimensional model with elements of singularity around the tip crack. The results were compared with the experiments and have been found to be in good correlation.

Study Anisotropy of a ductile iron class 80-60-03 hardening

This paper studies the effect of anisotropy in the propagation of surface cracks to identify areas of potential failure, and thus implement methods that increase the resistance of the phases created in the surface hardened cast iron ductile boride by the process. On the other hand assesses the influence of residual stresses using the fracture toughness microindentacion by Palmqvist cracks regime taking the perpendicular and parallel cracks generated in the hard surface, with samples of 6 h and 8 h, 900 °C treatment of boriding, with loads of 1.9 and 2.9 N. Where the value of at (kc) > (kc) > (kc) (θ) a constant distance of 30 microns. Also the phases present were determined by X-ray diffraction (XRD) and scanning electron microscopy (EDS), finally adherence is determined by the indentation technique HRC.